Effect of Three Operating Variables on Degradation of Direct Blue 199 by TiO2 Immobilized into a Polymer surface: Response Surface Methodology

This work aims to study the photodegradation of Direct Blue 199 dye. The investigation was performed using titanium dioxide-based films immobilized on a polymethyl methacrylate (PMMA) polymer, by a promising low coast technique. The characterization of the films by X-ray diffractometry, fourier transform infrared spectroscopy, scanning electron microscopy, UV-Visible transmittance, and fluorescence spectroscopy revealed the deposition of 13.76% by mass of TiO2 with excellent adhesion to the polymer surface. However, the evaluation of the influence of three parameters (pH, initial TiO2 concentration, H2O2 concentration) on the efficiency of color removal in aqueous solution under UV irradiation on suspended semiconductors, have been performed using the response surface methodology based on experimental design. We therefore found the following optimum conditions: pH= 8, [TiO2] = 1369.29 mg.L-1, [H2O2] = 40 mmol.L-1 which led to a discoloration efficiency of 85 %. The results were then used to evaluate the performance of the prepared photocatalyst films, which showed a strong capacity to absorb the dye due to the appearance of pores relative to the preparation procedure, in addition to their catalytic effect. The kinetic of decolorization under optimum conditions was well fitted to the pseudo-first-order kinetic model.